1. Field of the Invention
The present invention relates to a group III nitride semiconductor light-emitting device having a non-light-emitting region in a light-emitting layer, and a method for producing the same.
2. Description of the Related Art
In a face-up-type group III nitride semiconductor light-emitting device, light emitted from a light-emitting layer positioned just below a p-pad electrode is reflected and absorbed by the p-pad electrode. As a technology to inhibit this, a technology that inhibits light emission by blocking off that current flow to a region overlapping the p-pad electrode in a planar view (the case of viewing from a direction vertical to a principal surface of the light-emitting layer; therein after the same), of the light-emitting layer, inhibits reflection and absorption of light by the p-pad electrode, and improves light extraction efficiency, is known (JP-A-10-229219 and JP-A-2010-80542).
In JP-A-10-229219, a p-pad electrode is formed by a material containing a metal having reactivity to nitrogen, such as Cr, V, Ti, Nb, Ta or Zr. A p-type layer is reacted with the metal having reactivity to nitrogen in an alloy treatment of the p-pad electrode to form nitrogen vacancies in the p-type layer. A high resistance region in the p-type layer under the p-pad electrode is formed and as a result, current does not flow under the p-pad electrode.
In JP-A-2010-80542, a p-pad electrode comprising Ni/Au is formed on a transparent electrode comprising ITO upper a p-type layer, and heat treatment is conducted at from 500 to 650° C. Contact resistance of a region of the transparent electrode under the p-pad electrode, become high, and as a result, current does not flow under the p-pad electrode.
On the other hand, even in a group III nitride semiconductor light-emitting device having a structure that a p-electrode and an n-electrode are provided up and down to achieve conduction in a longitudinal direction (the direction vertical to a principal surface of a substrate) and having a structure that light is extracted from an n-electrode side using a high reflective metal p-electrode such as Ag (such a device can be produced, for example, using laser lift-off technology or using a conductive substrate such as a GaN substrate as a growth substrate), a technology making a region overlapping an n-electrode in a planar view, of a light-emitting layer to emit light, thereby improving light extraction efficiency is known. In this case, a region just below an n-electrode, of the light-emitting layer does not emit light by methods in which an insulating film is provided between a p-type layer and the p-electrode, a method in which the p-electrode is provided on only a region other than a region just below the n-electrode, or an insulating film is provided on a region just below the n-electrode, and a p-electrode is not provided.
However, the conventional method of forming an insulating layer and providing a non-light-emitting region as described above had the problem that many steps are required, resulting in the increase in production cost. Furthermore, in the methods disclosed in JP-A-10-229219 and JP-A-2010-80542, an electrode material is limited, and the methods could not be applied to the case of using high reflective metal such for Ag as a p-electrode.